From Longman Dictionary of Contemporary Englishin all innocencein all innocenceHARM/BE BAD FORif you do or say something in all innocence, you have no intention of doing harm or of offending anyone → innocence
Examples from the Corpus
in all innocence• His alibi turns out to have been provided, in all innocence, by his twin!• The offended divinity gave not a thought to whether the youth had purposely insulted her or had come there in all innocence. 